# Athanasios Vasilakos

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## Publications (5)0 Total impact

• Source
##### Article:Polynomial Bottleneck Congestion Games with Optimal Price of Anarchy
Rajgopal Kannan, Costas Busch, Athanasios Vasilakos
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ABSTRACT: We study {\em bottleneck congestion games} where the social cost is determined by the worst congestion of any resource. These games directly relate to network routing problems and also job-shop scheduling problems. In typical bottleneck congestion games, the utility costs of the players are determined by the worst congested resources that they use. However, the resulting Nash equilibria are inefficient, since the price of anarchy is proportional on the number of resources which can be high. Here we show that we can get smaller price of anarchy with the bottleneck social cost metric. We introduce the {\em polynomial bottleneck games} where the utility costs of the players are polynomial functions of the congestion of the resources that they use. In particular, the delay function for any resource $r$ is $C_{r}^\M$, where $C_r$ is the congestion measured as the number of players that use $r$, and $\M \geq 1$ is an integer constant that defines the degree of the polynomial. The utility cost of a player is the sum of the individual delays of the resources that it uses. The social cost of the game remains the same, namely, it is the worst bottleneck resource congestion: $\max_{r} C_r$. We show that polynomial bottleneck games are very efficient and give price of anarchy $O(|R|^{1/(\M+1)})$, where $R$ is the set of resources. This price of anarchy is tight, since we demonstrate a game with price of anarchy $\Omega(|R|^{1/(\M+1)})$, for any $\M \geq 1$. We obtain our tight bounds by using two proof techniques: {\em transformation}, which we use to convert arbitrary games to simpler games, and {\em expansion}, which we use to bound the price of anarchy in a simpler game.
10/2010;
• ##### Article:Computational Intelligence in Management of ATM Networks - A Survey of Current State of Research
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ABSTRACT: Designing effective control strategies for Asynchronous Transfer Mode (ATM) networks is known to be difficult because of the complexity of the structure of networks, nature of the services supported, and variety of dynamic parameters involved. Additionally, the uncertainties involved in identification of the network parameters cause analytical modeling of ATM networks to be almost impossible. This renders the application of classical control system design methods (which rely on the availability of these models) to the problem even harder. Consequently, a number of researchers are looking at alternative non-analytical control system design and modeling techniques that have the ability to cope with these difficulties to devise effective, robust ATM network management schemes. Those schemes employ artificial neural networks, fuzzy systems and design methods based on evolutionary computation. In this survey, the current state of ATM network management research employing these techniques as reported in the technical literature is summarized. The salient features of the methods employed are reviewed. Key words Computational intelligence, ATM networks, fuzzy systems, neural networks, evolutionary computation 1
09/2001;
• ##### Article:A'cbd5ef%244g
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ABSTRACT: Designing effective control strategies for Asynchronous Transfer Mode (ATM) networks is known to be difficult because of the complexity of the structure of networks, nature of the services supported, and variety of dynamic parameters involved. Additionally, the uncertainties involved in identification of the network parameters cause analytical modeling of ATM networks to be almost impossible which renders the application of classical control system design methods (which rely on the availability of these models) into the problem even harder.
09/2001;
• ##### Article:Computational Intelligence in Management of ATM Networks: A Survey of Current State of Research
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ABSTRACT: Designing effective control strategies for Asynchronous Transfer Mode (ATM) networks is known to
04/2001;
• ##### Article:Computational Intelligence in Management of ATM
[show abstract] [hide abstract]
ABSTRACT: Designing effective control strategies for Asynchronous Transfer Mode (ATM) networks is known to be difficult because of the complexity of the structure of networks, nature of the services supported, and variety of dynamic parameters involved. Additionally, the uncertainties involved in identification of the network parameters cause analytical modeling of ATM networks to be almost impossible.
02/2001;